Compositions Formed from Plant Extracts and Methods of Preparation Thereof

ABSTRACT

Embodiments described herein relate generally to plant extract compositions and methods to isolate fatty acid esters derived from crosslinked polyesters. Particular embodiments are directed to methods of preparing compositions of fatty acid esters by treating crosslinked polyesters or other crosslinked networks with an acid and an alcohol.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/US2017/062399, filed Nov. 17, 2017, which claims priority to and thebenefit of U.S. Provisional Patent No. 62/423,337, filed Nov. 17, 2016,the contents of which are hereby incorporated by reference in theirentirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to compositions formed from plantextracts, and to methods of forming the same.

BACKGROUND

Common agricultural products are susceptible to degradation anddecomposition (i.e., spoilage) when exposed to the environment. Suchagricultural products can include, for example, eggs, fruits,vegetables, produce, seeds, nuts, flowers, and/or whole plants(including their processed and semi-processed forms). Non-agriculturalproducts (e.g., vitamins, candy, etc.) are also vulnerable todegradation when exposed to the ambient environment. The degradation ofthe agricultural products can occur via abiotic means as a result ofevaporative moisture loss from an external surface of the agriculturalproducts to the atmosphere and/or oxidation by oxygen that diffuses intothe agricultural products from the environment and/or mechanical damageto the surface and/or light-induced degradation (i.e.,photodegradation). Furthermore, biotic stressors such as, for example,bacteria, fungi, viruses, and/or pests can also infest and decompose theagricultural products.

Conventional approaches to preventing degradation, maintaining quality,and increasing the life of agricultural products include refrigerationand/or special packaging. Refrigeration requires capital-intensiveequipment, demands constant energy expenditure, can cause damage orquality loss to the product if not carefully controlled, must beactively managed, and its benefits are lost upon interruption of atemperature-controlled supply chain. Special packaging can also requireexpensive equipment, consume packaging material, increase transportationcosts, and require active management. Despite the benefits that can beafforded by refrigeration and special packaging, the handling andtransportation of the agricultural products can cause surface abrasionor bruising that is aesthetically displeasing to the consumer and servesas points of ingress for bacteria and fungi. Moreover, the expensesassociated with such approaches can add to the cost of the agriculturalproduct.

The cells that form the aerial surface of most plants (such as higherplants) include an outer envelope or cuticle, which provides varyingdegrees of protection against water loss, oxidation, mechanical damage,photodegradation, and/or biotic stressors, depending upon the plantspecies and the plant organ (e.g., fruit, seeds, bark, flowers, leaves,stems, etc.). Cutin, which is a biopolyester derived from cellularlipids, forms the major structural component of the cuticle and servesto provide protection to the plant against environmental stressors (bothabiotic and biotic). The thickness, density, as well as the compositionof the cutin (i.e., the different types of monomers that form the cutinand their relative proportions) can vary by plant species, by plantorgan within the same or different plant species, and by stage of plantmaturity. The cutin-containing portion of the plant can also containadditional compounds (e.g., epicuticular waxes, phenolics, antioxidants,colored compounds, proteins, polysaccharides, etc.). This variation inthe cutin composition as well as the thickness and density of the cutinlayer between plant species and/or plant organs and/or a given plant atdifferent stages of maturation can lead to varying degrees of resistancebetween plant species or plant organs to attack by environmentalstressors (i.e., water loss, oxidation, mechanical injury, and light)and/or biotic stressors (e.g., fungi, bacteria, viruses, insects, etc.).

SUMMARY

Embodiments described herein relate generally to plant extractcompositions and methods to isolate cutin-derived monomers, oligomers,and/or their esters, and mixtures thereof, in particular forapplications in agricultural coating formulations. Particularembodiments are directed to methods of preparing compositions of fattyacid esters by treating crosslinked polyesters or other crosslinkednetworks with an acid and an alcohol.

In a first aspect, a method of preparing a composition comprising fattyacid esters includes providing a crosslinked polyester comprising fattyacids, treating the crosslinked polyester with an acid and an alcohol,and removing the acid and the alcohol to isolate the resulting fattyacid esters.

In a second aspect, a method of preparing a composition comprisingesters includes providing a crosslinked network including hydrolyzableor transesterifiable bonds, treating the crosslinked network with anacid and an alcohol, and removing the acid and the alcohol to isolatethe resulting esters.

In a third aspect, a method of preparing a composition comprisingcutin-derived monomers, oligomers, esters, or combinations thereofincludes providing cutin obtained from plant matter, and treating thecutin with a solvent, thereby causing the cutin to decompose into thecutin-derived monomers, oligomers, esters, or combinations thereof. Themethod further includes removing the solvent to isolate thecutin-derived monomers, oligomers, esters, or combinations thereof. Theresulting composition is characterized as being in the form of a solidpowder with little or no coloration.

In a fourth aspect, a method of forming a protective coating on asubstrate includes obtaining fatty acid esters, wherein the obtaining ofthe fatty acid esters comprises treating a crosslinked polyestercomprising fatty acids with an acid and an alcohol, and removing theacid and alcohol to isolate the resulting fatty acid esters. The methodfurther includes causing the fatty acid esters to be applied to asurface of the substrate to form the protective coating.

In a fifth aspect, a method of preparing a composition comprisingcutin-derived monomers, oligomers, esters, or combinations thereof fromcutin-containing plant matter includes obtaining cutin from thecutin-containing plant matter and adding the cutin to a solventcomprising an acid and an alcohol to form a first mixture. The methodfurther includes removing the solvent to isolate the cutin-derivedmonomers, oligomers, esters, or combinations thereof. The resultingcutin-derived monomers, oligomers, esters, or combinations thereof cancomprise one or more compounds of Formula I:

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², m, n, and oare as described below.

Methods and formulations described herein can each include one or moreof the following steps or features, either alone or in combination withone another. The crosslinked polyester or crosslinked network can benaturally occurring. The crosslinked polyester or crosslinked networkcan be derived from plant matter. The crosslinked polyester orcrosslinked network can be cutin. The cutin can be derived from plantskins. Treating the crosslinked polyester or crosslinked network withthe acid and the alcohol can include suspending or dissolving thecrosslinked polyester or crosslinked network and the acid in the alcoholto form a solution. The acid can be a strong acid. A concentration ofthe acid in the solution can be greater than 100 μmol/L. The solutioncan further comprise a non-reactive secondary solvent.

The crosslinked polyester or crosslinked network can contain endogenouswater. Treating the crosslinked polyester with the acid and the alcoholcan further comprise heating the crosslinked polyester, the acid, andthe alcohol. Heating the crosslinked polyester, the acid, and thealcohol can comprise refluxing the polyester, the acid, and the alcoholat the boiling point of the alcohol. The polyester, the acid, and thealcohol can be heated in a sealed vessel above the boiling point of thealcohol. The alcohol can comprise ethanol, methanol, propanol, glycerol,isopropanol, or combinations thereof. The alcohol can be a primary orsecondary alcohol. Removing the acid can comprise neutralizing the acid.Removing the alcohol can comprise evaporating the alcohol.

The acid can be sulfuric acid, triflic acid, hydrochloric acid,hydrobromic acid, hydroiodic acid, para-toluenesulfonic acid, or acombination thereof. The acid can be catalytic. The acid can be utilizedin superstoichiometric amounts. A molar ratio of the alcohol to thefatty acids can be greater than 1. The fatty acids of the crosslinkedpolymer or crosslinked network can comprise 16-hydroxy hexadecanoicacid, 9,16-dihydroxyhexadecanoic acid, 10,16-dihydroxyhexadecanoic acid,18-hydroxysteric acid, 18-hydroxy-(9Z)-octadec-9-enoic acid,9,10-epoxy-18-hydroxy octadecanoic acid, 9,10,18-trihydroxyoctadecanoicacid, or a combination thereof. The resulting fatty acid esters cancomprise ethyl 16-hydroxyhexadecanoate, ethyl9,16-dihydroxyhexadecanoate, ethyl 10,16-dihydroxyhexadecanoate, ethyl18-hydroxyoctadecanoate, ethyl 18-hydroxy-(9Z)-octadec-9-enoate, ethyl9,10-epoxy-18-hydroxyoctadecanoate, ethyl9,10,18-trihydroxyoctadecanoate, or a combination thereof.

The method can be characterized as only requiring a single step toobtain the resulting fatty acid esters from the crosslinked polyester orcrosslinked network. The fatty acid esters formed by any of the methodsdescribed herein can be applied to the surface of a substrate to form aprotective coating. The substrate can be an edible substrate. Thesubstrate can be a piece of produce. The substrate can be plant matter.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic flow diagram of a first exemplary method forpreparing a composition.

FIGS. 2A and 2B are schematic representations of reactions associatedwith a step of the method of FIG. 1.

FIG. 3 is a schematic flow diagram of a second exemplary method forpreparing a composition.

FIG. 4 is a schematic representation of a reaction associated with astep of the method of FIG. 3.

FIGS. 5 and 6 illustrate results obtained from preparing a compositionaccording to the method of FIG. 3.

FIGS. 7A, 7B, 7C, 7D, 7E, 7F, 7G, and 7H show the chemical structure of10,16-dihydroxyhexadecanoic acid, 10,18-dihydroxyoctadecanoic acid,9,16-dihydroxyhexadecanoic acid, 9,18-dihydroxyoctadecanoic acid,9,10,16-trihydroxyhexadecanoic acid, 9,10,18-trihydroxyoctadecanoicacid, 9,10-epoxy-16-hydroxyhexadecanoic acid, and9,10-epoxy-18-hydroxyoctadecanoic acid, respectively.

FIGS. 8A, 8B, 8C, 8D, 8E, 8F, 8G, and 8H show the chemical structure ofethyl 10,16-dihydroxyhexadecanoate, ethyl 10,18-dihydroxyoctadecanoate,ethyl 9,16-dihydroxyhexadecanoate, ethyl 9,18-dihydroxyoctadecanoate,ethyl 9,10,16-trihydroxyhexadecanoate, ethyl9,10,18-trihydroxyoctadecanoate, ethyl9,10-epoxy-16-hydroxyhexadecanoate, and ethyl9,10-epoxy-18-hydroxyoctadecanoic, respectively.

FIGS. 9A, 9B, 9C, 9D, 9E, 9F, 9G, and 9H show the chemical structure ofmethyl 10,16-dihydroxyhexadecanoate, methyl10,18-dihydroxyoctadecanoate, methyl 9,16-dihydroxyhexadecanoate, methyl9,18-dihydroxyoctadecanoate, methyl 9,10,16-trihydroxyhexadecanoate,methyl 9,10,18-trihydroxyoctadecanoate, methyl9,10-epoxy-16-hydroxyhexadecanoate, and methyl9,10-epoxy-18-hydroxyoctadecanoate, respectively.

FIGS. 10A, 10B, 10C, 10D, 10E, 10F, 10G, and 10H show the chemicalstructure of 2,3-dihydroxypropyl 10,16-dihydroxyhexadecanoate,2,3-dihydroxypropyl 10,18-dihydroxyoctadecanoate, 2,3-dihydroxypropyl9,16-dihydroxyhexadecanoate, 2,3-dihydroxypropyl9,18-dihydroxyhexadecanoate, 2,3-dihydroxypropyl9,10,16-trihydroxyhexadecanoate, 2,3-dihydroxypropyl9,10,18-trihydroxyoctadecanoate, 2,3-dihydroxypropyl9,10-epoxy-16-hydroxyhexadecanoate, and 2,3-dihydroxypropyl9,10-epoxy-18-hydroxyoctadecanoate, respectively.

FIGS. 11A, 11B, 11C, 11D, 11E, 11F, 11G, and 11H show the chemicalstructure of 1,3-dihydroxypropan-2-yl 10,16-dihydroxyhexadecanoate,1,3-dihydroxypropan-2-yl 10,18-dihydroxyoctadecanoate,1,3-dihydroxypropan-2-yl 9,16-dihydroxyhexadecanoate,1,3-dihydroxypropan-2-yl 9,18-dihydroxyhexadecanoate,1,3-dihydroxypropan-2-yl 9,10,16-trihydroxyhexadecanoate,1,3-dihydroxypropan-2-yl 9,10,18-trihydroxyoctadecanoate,1,3-dihydroxypropan-2-yl 9,10-epoxy-16-hydroxyhexadecanoate, and1,3-dihydroxypropan-2-yl 9,10-epoxy-18-hydroxyoctadecanoate,respectively.

FIGS. 12 and 13 illustrate characterization of a composition preparedaccording to the method of FIG. 3.

FIG. 14 depicts various cutin-derived monomers which may be obtainedfrom the methods described herein and/or which may be treated accordingto the methods described herein for the purpose of coating and/orpreserving fruits and vegetables.

FIG. 15 depicts an epoxide ring-opening reaction. The products ofepoxide ring-opening reactions may be treated according to the methodsdescribed herein for the purpose of coating and/or preserving fruits andvegetables.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

The biopolyester cutin forms the main structural component of thecuticle that composes the aerial surface of most land plants and plays asignificant role in providing plants a protective barrier against bothabiotic and biotic stressors. The thickness, density, as well as thecomposition of the cutin (i.e., the different types of monomers thatform the cutin and their relative proportions) can vary by plantspecies, by plant organ within the same or different plant species, andby stage of plant maturity. These variations can define the amount,degree, or quality of protection (and degree of plasticity) offered bythe cutin layer to the plant or plant organ against environmental and/orbiotic stressors. Cutin is formed from a mixture of polymerized mono-and/or polyhydroxy fatty acids and embedded cuticular waxes. Among thehydroxy fatty acids, polyhydroxy fatty acids (e.g., dihydroxy fattyacids or trihydroxy fatty acids), once esterified, can in some casesform tightly bound networks with high crosslink density and lowerpermeability as compared to monohydroxy fatty acids and can therebyprovide better protection against environmental stressors.

Embodiments described herein relate generally to plant extractcompositions and to methods of preparing plant extract compositions thatinclude fatty acid esters (monomers and/or their oligomers) derived fromcutin or other crosslinked polyesters. In particular, methods describedherein allow for generation of fatty acid esters directly by treating acrosslinked polyester (e.g., cutin) which includes a mixture ofpolymerized mono- and/or polyhydroxy fatty acids with an acid and analcohol. Compositions which include the resulting fatty esters can, forexample, be subsequently applied to other plant or agricultural productsin order to form a protective material (e.g., a coating) over theproducts, or to enhance or modify existing coatings (either naturallyoccurring or deposited coatings) which are on the outer surface of theproducts. The applied coatings can, for example, serve to protect theproducts from biotic stressors such as bacteria, fungi, viruses, and/orpests. The applied coatings can also (or alternatively) serve toincrease the shelf life of produce without refrigeration, and/or tocontrol the rate of ripening or respiration of produce.

Conventional methods for producing fatty acid esters typically involveperforming a first step (or series of steps) to isolate fatty acids(e.g., fatty acid monomers and/or oligomers) and then subsequentlyperform a second step (or series of steps) to convert the fatty acids toesters, for example via Fischer esterification. Methods described hereinprovide for a process for generating fatty acid esters directly from apolyester such as cutin, without the need to first isolate the fattyacid monomers/oligomers. Accordingly, methods of preparing a compositioncomprising fatty acid esters can include (i) providing a crosslinkedpolyester (e.g., cutin) comprising fatty acids, (ii) treating thepolyester with an acid and an alcohol, and (iii) removing the acid andalcohol to isolate the resulting fatty acid esters. In particularembodiments described herein, the crosslinked polyester is cutin derivedfrom plant matter.

As used herein, “plant matter” refers to any portion of a plant,including, for example, fruits (in the botanical sense, including fruitpeels and juice sacs), leaves, stems, barks, seeds, flowers, peels, orroots.

A first method 100 for treating (e.g., depolymerizing) cutin to obtain aplant extract composition is illustrated in FIG. 1. The method 100includes first treating plant matter to at least partially separate acutin-containing portion from a non-cutin-containing portion of theplant matter (step 102). Treating the plant matter can include, forexample, thermal treating of the plant matter. The thermal treating caninclude, for example, heating the plant matter (e.g., with steam, inwater or in another solvent), freezing the plant, subjecting the plantmatter to cyclic thermal treatments, or drying. The plant matter caninclude any suitable plant matter or other agricultural product such as,for example, fruits (including fruit peels and juice sacs), leaves,stems, barks, seeds, flowers, peels, or roots. In some embodiments, theplant matter can include agricultural waste products such as, forexample, tomato peels, grape skins, apple peels, pepper peels, lemonpeels, lemon leaf, lime peels, lime leaf, orange peels, orange leaf,orange fruit, clementine leaf, clementine fruit, mandarin leaf, mandarinfruit, pea seeds, grapefruit peels, grapefruit leaf, grapefruit seeds,papaya peels, cherry fruits, cranberry skins, coffee cherries, grassclippings, or any other plants or portions of plants that can yield anyembodiment of the plant extract compositions described herein. In someembodiments, the plant matter can be a fruit (e.g., a tomato, cranberry,or grape) and the cutin-containing portion can be a peel of the fruit(e.g., a tomato peel or cranberry skin or grape skin) such that theboiling can at least partially separate the peel from the fruit. Thefruit can be washed to remove surface residue, waxes, or other debrisbefore operation 102. Furthermore, the fruit can be cut into halves,quarters, or small pieces or ground to finer pieces and then boileduntil the peels or skins are visibly separated from the fruit pulp.

The method 100 can optionally include mechanically processing the plantmatter to at least partially separate the cutin-containing portion fromthe non-cutin-containing portion of the plant matter (step 104). Themechanical process can be performed before and/or after thermaltreatment of the plant matter (i.e., 102) (e.g., boiling of the plantmatter in water) to facilitate separation of the cutin-containingportion from the non-cutin-containing portion of the plant matter.Suitable mechanical processes can include, for example, centrifugation,(ultra)sonication, pressing, ball milling, grinding, etc. In someembodiments, mechanical separation can include separating a fruit peelfrom the fruit pulp. In some embodiments, mechanical removal of the pulpmight not be performed and the fruit skins (e.g., waste fruit skins leftover after processing of the fruit) may be macerated, blended, cut,shredded, food processed, or otherwise subjected to some othermechanical treatment operation to physically break down the fruit skinsinto smaller or finer pieces. In some embodiments, a plurality ofintermediate mechanical processes can be used to obtain the plantextract composition. For example, a mechanical step can be used toseparate the cutin from the non-cutin-containing portion, as describedherein, or be used to augment any other operation included in the method100. Such mechanical processes can include any of the mechanicalprocesses described herein such as, for example, centrifugation,sonication, (ultra)sonication, milling, grinding, filtration, etc.

The cutin-containing portion is then optionally heated (e.g., boiled) ina mixture of ammonium oxalate and oxalic acid to separate the cutin fromthe non-cutin-containing portion (step 106). Optionally this process canalso be achieved (or assisted) using enzymes capable of breaking downpolysaccharides or pectin. For example, the cutin can include thecuticular layer of the plant matter. The heating in the ammonium oxalateand oxalic acid mixture disrupts the pectinaceous glue that attaches thecuticle to the underlying cells of the plant matter and helps releasethe cuticle. Furthermore, this step disrupts the pectinaceous glue thatis found within primary cell walls and between plant cells (e.g., in themiddle lamella that binds neighboring cells), aiding in the isolation ofa cutin-containing portion. In this manner, the ammonium oxalate andoxalic acid solution can facilitate at least partial chemical detachmentof remaining debris from the cutin-containing portion of the plant(e.g., removal of any remaining pulp from the fruit peel). The heatingcan be performed at any suitable temperature (e.g., 35 degrees Celsius,50 degrees Celsius, 55 degrees Celsius, 60 degrees Celsius, 65 degreesCelsius, 70 degrees Celsius, 75 degrees Celsius, 80 degrees Celsius, 85degrees Celsius, 90 degrees Celsius, 95 degrees Celsius, or 100 degreesCelsius, inclusive of all ranges and values therebetween) and for anysuitable time (this process can be accelerated if carried out underelevated pressure). For example, in some embodiments, thecutin-containing portion can be heated in the mixture of ammoniumoxalate and oxalic acid at a temperature of about 75 degrees Celsius forabout 24 hours. In some embodiments, the portion of the plant, forexample, the fruit peel, after treatment with the ammonium oxalate andoxalic acid solution, can be isolated by filtration and dried (e.g.,air-dried under ambient conditions, oven-dried or freeze-dried) toremove any residual water.

In some embodiments, the cutin can optionally be treated with an enzyme(step 108). For example, the cutin can be treated with an enzyme such asa carbohydrate-hydrolyzing enzyme to digest or otherwise removecarbohydrates (e.g., cellulose or pectin) attached to or embedded withinthe cutin. Such enzymes can include, for example, naturally derived orsynthetic cellulases, pectinases, and hemicellulases. The enzymaticdegradation can be used before, after, or otherwise in place of step 106to obtain the cutin from the non-cutin-containing portion. In someembodiments, the reverse process may be employed, wherein the cutin istreated with an enzyme that can at least partially depolymerize thecutin to yield any combination of cutin-derived oligomers andcutin-derived monomers and to leave behind the non-cutin-containingcomponents, which could be filtered out or otherwise separated. Suchenzymes can include, for example, cutinases, esterases, or lipases.

Optionally, the cutin is refluxed or subjected to soxhlet extraction inat least one suitable solvent (e.g., chloroform and/or methanol) toremove soluble waxes or polar impurities from the cutin (step 110). Forexample, the cutin can be refluxed or subjected to soxhlet extractiononly in chloroform, refluxed or soxhlet extracted in chloroform followedby refluxing or soxhlet extraction in methanol, refluxed or subjected tosoxhlet extraction only in methanol, or refluxed or subjected to soxhletextraction in a mixture of chloroform and methanol, or any othersuitable solvent(s) (or combinations thereof) in which the wax and/orpolar components are soluble. In some embodiments, the cutin can berefluxed in a dilute solution of a strong base (e.g., potassiumhydroxide in water or in alcoholic solvent), or a solution of amoderately strong or weak base (e.g., potassium carbonate in water or inalcoholic solvent) to remove soluble pigmented impurities.Alternatively, removal of residual waxes and remaining solublecomponents can be achieved using supercritical CO₂ or supercritical H₂O.The refluxing can be performed at any suitable temperature and for anysuitable length of time. For example, in some embodiments, the cutin canbe refluxed in chloroform at about 60-65 degrees Celsius for about 24-36hours to remove any wax and/or non-polar compounds embedded in thecutin. This can be followed by refluxing in methanol at 65-70 degreesCelsius for about 4-12 hours, for example, to remove any polar organiccomponents (e.g., flavonoids and flavonoid glycosides) present in thecutin. The completion of the operation can be determined by the clarityof solvents. For example, the process can be monitored withinstrumentation (e.g., NMR, GC-MS, React-IR, FTIR, spectrophotometry,etc.) configured to analyze the clarity of the solvents and can continueuntil a predetermined clarity is achieved. Each of the chloroform and/ormethanol extraction processes can be performed in any apparatus capableof refluxing (i.e., recirculating and/or recycling) the solvents suchas, for example, a reaction flask equipped with a condenser, a Soxhletapparatus, a Kumagawa extractor, an ultrasound assisted extractor, arobot automated extractor, or any other suitable extraction apparatus.Such an apparatus can, for example, reduce the amount of solvent used inthe extraction process. Any other solvent or combinations thereof (i.e.,a binary or ternary mixture) can be used to wash out undesiredimpurities. Suitable solvents can include, for example, diethyl ether,dichloromethane, hexane, petroleum ether, ethyl acetate, acetone,isopropanol, ethanol, acetonitrile, supercritical carbon dioxide,supercritical water, water, and mixtures thereof. In some embodiments,multiple extraction steps in one or more solvents can also be performed.In some embodiments, intermediate enzymatic treatment steps can also beperformed between the solvent extraction processes, for example, toliberate undesired compounds from the cutin. The solution obtained afteroperation 110 can include a relatively pure sample of the cutin includedin the portion of the plant along with any residually attached orembedded polysaccharides (e.g., cellulose), plant metabolites (e.g.,flavonoids), and/or proteins.

The cutin is then heated in a base solution (e.g., metal alkoxide ormetal hydroxide dissolved in a solvent such as ethanol or methanol orwater or combinations thereof) to at least partially depolymerize thecutin and obtain a plant extract including a plurality of cutin-derivedmonomers, oligomers, or combinations thereof (step 112). The pH of thesolution can, for example, be in a range of about 10 to 14, for examplein a range of 12 to 14. The metal alkoxide can include, for example,sodium methoxide, sodium ethoxide, sodium iso-propoxide, sodiumn-propoxide, sodium iso-butoxide, sodium n-butoxide, potassiummethoxide, potassium ethoxide, potassium iso-propoxide, potassiumn-propoxide, potassium iso-butoxide, or potassium n-butoxide. The metalhydroxide can include, for example, Group I or Group II metalhydroxides, such as lithium, sodium, potassium, calcium, rubidium, orcesium hydroxide. Also included are precursors or compounds that willgenerate alkoxide or hydroxide in a suitable reaction medium (such asneat metals (e.g., sodium metal) or oxides in methanol, or ammonia inwater). Refluxing of the cutin in the presence of the metal alkoxide ormetal hydroxide can be performed at any suitable temperature and for anysuitable length of time such as, for example, at about 65 degreesCelsius for about 24 hours. In some embodiments, the temperature and/orthe refluxing time can be such that the cutin is only partiallydepolymerized to yield a predetermined combination of oligomers andmonomers. In some embodiments, the temperature and/or the refluxing timecan be adjusted such that the cutin is mostly depolymerized by the metalalkoxide or metal hydroxide into a plurality of cutin-derived monomersand/or oligomers. In some embodiments, the refluxing in the metalalkoxide or metal hydroxide can be performed in a mixture of the metalalkoxide or metal hydroxide and a solvent, for example, methanol,ethanol, hexane, toluene, etc. In some embodiments, the solvent caninclude methanol. The concentration of metal alkoxide, solvent, and/orthe pH of the solution can, for example, facilitate the preservation ofthe depolymerized cutin components in monomeric form, which can preventoligomerization or repolymerization of the liberated cutin monomersincluded in the plant extract. Although an acid catalyst for thereaction (utilizing methods further described below) could be used inplace of the base catalyst, base catalysts are commonly used fortransesterification of oils, as in many cases the reaction rate can behigher than that for an acid catalyst.

In efforts to obtain fatty acid ester products (or oligomers thereof)from the depolymerization step 112 of method 100, the refluxing of thecutin in the presence of the metal alkoxide was carried out by theinventors of the present disclosure in anhydrous reagents and anhydroussolvents (e.g., ethanol) in a closed, nitrogenous atmosphere.Specifically, cutin obtained from tomato pomace was refluxed in asolution comprising sodium ethoxide (prepared by dissolving sodium inethanol) according to the process described in Example 2 below in orderto favor ester formation over saponification and acid formation. Theexpected reaction is schematically represented in FIG. 2A for the caseof an anhydrous solution comprising sodium ethoxide dissolved inethanol. Referring to FIG. 2A, cutin 202 is represented by a crosslinkednetwork of polyhydroxy fatty acids, where R and R′ represent adjacentfatty acid units. Depolymerization of the cutin 202 by the sodiumethoxide present in the EtOH in the absence of water is expected to formisolated ethyl esters 204, as shown in FIG. 2A.

FIG. 2B is a schematic representation of the depolymerization reactionfor the case where water is present in the solution. In this case, thereaction produces both ethyl esters 204 and carboxylic acid 206. Asfurther shown in FIG. 2B, the base in the solution causes the carboxylicacid 206 to be converted to carboxylate 208. If enough water is presentin the solution, substantially all of the depolymerized product isdriven to the carboxylic acid 206 and then converted to the carboxylate208 by the base in the solution, such that no measurable concentrationof ethyl esters 204 is present in the resulting composition.

Without wishing to be bound by theory, the inventors of the currentdisclosure observed that despite extensive drying and/or other effortsto ensure that no water was present in the reaction during cutindepolymerization according to Example 2, the apparently dry cutinappeared to contain sufficient endogenous water to result in all of thedepolymerized product being shunted to the carboxylate 208.Consequently, no substantial concentration of esters 204 could bedetected in the resulting extract composition.

A second method 300 for depolymerizing cutin to obtain a plant extractcomposition is illustrated in FIG. 3. Steps 302, 304, 306, 308, and 310,in which cutin is obtained from plant matter, are the same as steps 102,104, 106, 108, and 110, respectively, of method 100 in FIG. 1. However,in step 312 of method 300, the cutin is refluxed in an acid and analcohol (rather than a base and an alcohol as in step 112 of method 100)in order to obtain a plant extract composition including cutin-derivedmonomers and/or oligomers.

The specific reaction associated with the second method 300, andspecifically with step 312, is schematically represented in FIG. 4 forthe case of a solution comprising an acid dissolved in ethanol. Thereaction in FIG. 4 assumes the presence of water in the solution (e.g.,endogenous water contained within the cutin). Similar to FIG. 2, in FIG.4 cutin 202 is represented by a crosslinked network of polyhydroxy fattyacids, where R and R′ represent adjacent fatty acid units.Depolymerization of the cutin 202 in the acidified solution in thepresence of water is expected to form ethyl esters 204 and carboxylicacid 206 in a state of equilibrium with one another, thus producing aplant extract composition including fatty acid esters (e.g., ethylesters 204). In step 312 of method 300, due to the absence of a basecatalyst, the carboxylic acid 206 is not converted to a carboxylate, asin method 100 and corresponding FIG. 2B. Consequently, the reaction isexpected to produce a composition comprising a mix of ethyl esters 204and carboxylic acid 206, where the product distribution approximatelyreflects the ratio of esterification partner to water.

In efforts to obtain a composition including fatty acid esters (oroligomers thereof) by way of method 300 (and in particular by utilizingstep 312 of method 300), the inventors of the subject matter in thecurrent application refluxed cutin obtained from tomato pomace in asolution comprising sulfuric acid dissolved in ethanol according to theprocess described in Example 3 below. Results are illustrated in FIGS. 5and 6. As shown in Example 3 and FIGS. 5 and 6, the process resulted inthe production and isolation of ethyl 10,16-dihydroxyhexdecanoate(herein “EtDHPA”).

It was found through extensive experimentation that a larger amount ofacid than predicted from catalytic calculations was needed to ensurehigh yields of products. For instance, under refluxing conditions, anincrease in both crude isolate and purified isolate was seen whenincreasing the equivalence of sulfuric acid used from 0.1 to 0.25 to 0.5to 1 to 2 equivalents, from negligible material to 8.1% isolated yield,over the course of 48 hours. Furthermore, the reaction couldadditionally be accelerated by sealing the system to generate pressure,such that the reaction could be conducted above the atmospheric boilingpoint of the solvent (see Example 4). A further increase in crudeisolate and purified isolate yields was seen when the temperature wasincreased from reflux (78° C.) to 100° C. to 120° C., with oneequivalent of acid, up to 14% isolated yield. However, without wishingto be bound by theory, there appears to be an upper limit, after whichthe isolated yield appears to decrease, as seen in FIGS. 5 and 6 (120°C., 2 eq. H₂SO₄, 48 hrs).

While EtDHPA 204 (in FIG. 4) can be produced by method 300 of FIG. 3with ethanol utilized as the alcohol and with a cutin source (or othercrosslinked polymer) that includes 10,16-dihydroxyhexadecanoic acid (oresters thereof) as a building block of the crosslinked network, othertypes of ethyl esters can be produced by method 300 using cutin fromplant sources (or other crosslinked polymers/networks) that are formedof different molecular building blocks. For example, cutin from tomatoestends to have a high proportion of C₁₆ fatty acids (e.g., fatty acidshaving a carbon chain length of 16) such as that of FIGS. 7A, 7C, 7E,and 7G, where FIG. 7A shows the chemical composition of10,16-dihydroxyhexadecanoic acid (700 in FIG. 7A), FIG. 7C shows thechemical composition of 9,16-dihydroxyhexadecanoic acid (704 in FIG.7C), FIG. 7E shows the chemical composition of9,10,16-trihydroxyhexadecanoic acid (708 in FIG. 7E), and FIG. 7G showsthe chemical composition of 9,10-epoxy-16-hydroxyhexadecanoic acid (712in FIG. 7G). Accordingly, ethyl esters that can be produced by method300 using cutin from tomatoes can include ethyl10,16-dihydroxyhexadecanoate (800 in FIG. 8A), ethyl9,16-dihydroxyhexadecanoate (804 in FIG. 8C), ethyl9,10,16-trihydroxyhexadecanoate (808 in FIG. 8E), and/or ethyl9,10-epoxy-16-hydroxyhexadecanoate (812 in FIG. 8G).

On the other hand, cutin from cranberries tends to have a highproportion of Cis fatty acids (e.g., fatty acids having a carbon chainlength of 18) such as that of FIGS. 7B, 7D, 7F, and 7H, where FIG. 7Bshows the chemical composition of 10,18-dihydroxyoctadecanoic acid (702in FIG. 7B), FIG. 7D shows the chemical composition of9,18-dihydroxyoctadecanoic acid (706 in FIG. 7D), FIG. 7F shows thechemical composition of 9,10,18-trihydroxyoctadecanoic acid (710 in FIG.7F), and FIG. 7H shows the chemical composition of9,10-epoxy-18-hydroxyoctadecanoic acid (714 in FIG. 7H). Accordingly,ethyl esters that can be produced by method 300 using cutin fromcranberries can include ethyl 10,18-dihydroxyoctadecanoate (802 in FIG.8B), ethyl 9,18-dihydroxyhexadecanoate (806 in FIG. 8D), ethyl9,10,18-trihydroxyoctadecanoate (810 in FIG. 8F), and/or ethyl9,10-epoxy-18-hydroxyoctadecanoate (814 in FIG. 8H).

Furthermore, alcohols other than (or in addition to) ethanol can be usedin the method 300 of FIG. 3, which can result in other types of estersbeing produced. For example, using methanol as the alcohol can result inthe production of methyl esters such as methyl10,16-dihydroxyhexadecanoate (900 in FIG. 9A), methyl10,18-dihydroxyoctadecanoate (902 in FIG. 9B), methyl9,16-dihydroxyhexadecanoate (904 in FIG. 9C), methyl9,18-dihydroxyhexadecanoate (906 in FIG. 9D), methyl9,10,16-trihydroxyhexadecanoate (908 in FIG. 9E), methyl9,10,18-trihydroxyoctadecanoate (910 in FIG. 9F), methyl9,10-epoxy-16-hydroxyhexadecanoate (912 in FIG. 9G), and/or methyl9,10-epoxy-18-hydroxyoctadecanoate (914 in FIG. 9H). Or, using glycerolas the alcohol can result in the production of glyceryl esters (e.g.,1-glyceryl or 2-glyceryl esters). For example, 1-glyceryl esters thatcan be produced include 2,3-dihydroxypropyl 10,16-dihydroxyhexadecanoate(1000 in FIG. 10A), 2,3-dihydroxypropyl 10,18-dihydroxyoctadecanoate(1002 in FIG. 10B), 2,3-dihydroxypropyl 9,16-dihydroxyhexadecanoate(1004 in FIG. 10C), 2,3-dihydroxypropyl 9,18-dihydroxyhexadecanoate(1006 in FIG. 10D), 2,3-dihydroxypropyl 9,10,16-trihydroxyhexadecanoate(1008 in FIG. 10E), 2,3-dihydroxypropyl 9,10,18-trihydroxyoctadecanoate(1010 in FIG. 10F), 2,3-dihydroxypropyl9,10-epoxy-16-hydroxyhexadecanoate (1012 in FIG. 10G), and/or2,3-dihydroxypropyl 9,10-epoxy-18-hydroxyoctadecanoate (1014 in FIG.10H). 2-glyceryl esters that can be produced include1,3-dihydroxypropan-2-yl 10,16-dihydroxyhexadecanoate (1100 in FIG.11A), 1,3-dihydroxypropan-2-yl 10,18-dihydroxyoctadecanoate (1102 inFIG. 11B), 1,3-dihydroxypropan-2-yl 9,16-dihydroxyhexadecanoate (1104 inFIG. 11C), 1,3-dihydroxypropan-2-yl 9,18-dihydroxyhexadecanoate (1106 inFIG. 11D), 1,3-dihydroxypropan-2-yl 9,10,16-trihydroxyhexadecanoate(1108 in FIG. 11E), 1,3-dihydroxypropan-2-yl9,10,18-trihydroxyoctadecanoate (1110 in FIG. 11F),1,3-dihydroxypropan-2-yl 9,10-epoxy-16-hydroxyhexadecanoate (1112 inFIG. 11G), and/or 1,3-dihydroxypropan-2-yl9,10-epoxy-18-hydroxyoctadecanoate (1114 in FIG. 11H).

In general, the method 300 in FIG. 3 can produce one or more compoundsof Formula I:

wherein:

R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are each independently —H,—OR¹³, —NR¹³R¹⁴, —SR¹³, halogen, —C₁-C₆ alkyl, —C₁-C₆ alkenyl, —C₁-C₆alkynyl, —C₃-C₇ cycloalkyl, aryl, or 5- to 10-membered ring heteroaryl,wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl isoptionally substituted with —OR¹³, —NR¹³R¹⁴, —SR¹³, or halogen;

R¹³ and R¹⁴ are each independently —H, —C₁-C₆ alkyl, —C₁-C₆ alkenyl, or—C₁-C₆ alkynyl;

R¹¹ is —H, -glyceryl, —C₁-C₆ alkyl, —C₁-C₆ alkenyl, —C₁-C₆ alkynyl,—C₃-C₇ cycloalkyl, aryl, or 5- to 10-membered ring heteroaryl, whereineach alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl isoptionally substituted with —OR¹³, —NR¹³R¹⁴, —SR¹³, or halogen;

R¹² is —OH, —H, —C₁-C₆ alkyl, —C₁-C₆ alkenyl, —C₁-C₆ alkynyl, —C₃-C₇cycloalkyl, aryl, or 5- to 10-membered ring heteroaryl, wherein eachalkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl is optionallysubstituted with —OR¹³, —NR¹³R¹⁴, —SR¹³, halogen, —COOH, or —COOR¹; and

m, n, and o are each independently an integer in the range of 0 to 30,and 0≤m+n+o≤30.

In some implementations, R¹, R², R³, R⁴, R⁵, R⁶, R⁸, R⁹, R¹⁰, and R¹² inFormula I are each H. Additionally, the method 300 in FIG. 3 can produceone or more compounds of Formula II:

wherein:

R¹, R², R⁵, R⁶, R⁹, R¹⁰, R¹¹, R¹² and R¹³ are each independently, ateach occurrence, —H, —OR¹⁴, —NR¹⁴R¹⁵, —SR¹⁴, halogen, —C₁-C₆ alkyl,—C₂-C₆ alkenyl, —C₂-C₆ alkynyl, —C₃-C₇ cycloalkyl, aryl, or heteroaryl,wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl isoptionally substituted with one or more —OR¹⁴, —NR¹⁴R¹⁵, —SR¹⁴, orhalogen;

R³, R⁴, R⁷, and R⁸ are each independently, at each occurrence, —H,—OR¹⁴, —NR¹⁴R¹⁵, —SR¹⁴, halogen, —C₁-C₆ alkyl, —C₂-C₆ alkenyl, —C₂-C₆alkynyl, —C₃-C₇ cycloalkyl, aryl, or heteroaryl wherein each alkyl,alkynyl, cycloalkyl, aryl, or heteroaryl is optionally substituted withone or more —OR¹⁴, —NR¹⁴R¹⁵, —SR¹⁴, or halogen; or

R³ and R⁴ can combine with the carbon atoms to which they are attachedto form a C₃-C₆ cycloalkyl, a C₄-C₆ cycloalkenyl, or 3- to 6-memberedring heterocycle; and/or

R⁷ and R⁸ can combine with the carbon atoms to which they are attachedto form a C₃-C₆ cycloalkyl, a C₄-C₆ cycloalkenyl, or 3- to 6-memberedring heterocycle;

R¹⁴ and R¹⁵ are each independently, at each occurrence, —H, —C₁-C₆alkyl, —C₂-C₆ alkenyl, or —C₂-C₆ alkynyl;

the symbol

represents a single bond or a cis or trans double bond;

-   -   n is 0, 1, 2, 3, 4, 5, 6, 7 or 8;    -   m is 0, 1, 2 or 3;    -   q is 0, 1, 2, 3, 4 or 5; and    -   r is 0, 1, 2, 3, 4, 5, 6, 7 or 8; and

R is selected from —H, —C₁-C₆ alkyl, —C₂-C₆ alkenyl, —C₂-C₆ alkynyl,—C₃-C₇ cycloalkyl, aryl, 1-glyceryl, 2-glyceryl, or heteroaryl.

In some implementations, R is selected from —H, —CH₃, or —CH₂CH₃. Themethod 300 described herein can be used to produce one or more of thefollowing methyl ester compounds:

The method 300 described herein can also be used to produce one or moreof the following ethyl ester compounds:

The method 300 described herein can also be used to produce one or moreof the following 2-glyceryl ester compounds:

The method 300 described herein can also be used to produce one or moreof the following 1-glyceryl ester compounds:

In some embodiments, the acid included in the solution used todepolymerize the crosslinked polyester is a strong acid. As used herein,a “strong acid” is one for which substantially all of the acid ionizes(dissociates) in a solution (provided there is sufficient solvent). Astrong acid has a pKa<−1.74.

In some embodiments, the polyester, the acid, and the alcohol are heatedin a sealed vessel above the atmospheric boiling point of the alcohol.This sealed vessel can allow higher temperatures to be reached, whichcan allow for shorter reaction times and/or less acid needed to obtainthe product.

The fatty acid esters obtained by way of method 300 can be used in avariety of applications. For example, they can be applied directly to aplant or other agricultural product to form a protective coating, asfurther described below. Or, the esters may serve as starting materialfor further chemical transformations, for example for the production offree fatty acids. Although free fatty acids can be extracted fromcrosslinked polymers such as cutin using other methods (e.g., usingmethod 100 of FIG. 1), forming free fatty acids via transesterificationof esters obtained by way of method 300 can result in more highlypurified product. For example, when methods 100 and 300 are each used todepolymerize cutin, the resulting crude extract in both cases is an oil.However, purification of the extract obtained by method 300 results inproduct which is a solid powder with little or substantially nocoloration, and when dissolved in a solvent produces a solution with alow viscosity. On the other hand, purification of the extract obtainedby method 100 results in product which remains oily with substantialcoloration, and when dissolved in a solvent produces a solution with asubstantially higher viscosity.

In some embodiments, the plant extract composition can be applieddirectly to a portion of a plant, e.g., to form a protective coating onthe plant. In some embodiments, the plant extract composition can beheated to modify the physical and/or chemical properties of thecomposition prior to and/or during and/or after the application process.In some embodiments, the plant extract composition can be dissolvedand/or suspended in a solvent, in aqueous solutions, or in a carrierliquid to form the coating. The solvent can include any polar,non-polar, protic, or aprotic solvents, including any combinationsthereof. Examples of solvents that can be used to dissolve the plantextract compositions described herein include water, methanol, ethanol,isopropanol, butanol, acetone, ethyl acetate, chloroform, acetonitrile,tetrahydrofuran, diethyl ether, methyl tert-butyl ether, any othersuitable solvent or a combination thereof. Aqueous solutions,suspensions, or emulsions of such plant extract compositions can besuitable for coating on agricultural products, for example, forming acoating on the agricultural product. For example, the aqueous solutions,suspensions, or emulsions can be applied to the surface of theagricultural product, after which the solvent can be removed (e.g., byevaporation or convective drying), leaving a protective coating formedfrom the plant extract composition on the surface of the agriculturalproduct.

In some embodiments, the coatings can be configured to change thesurface energy of the agricultural product. Various properties ofcoatings described herein can be adjusted by tuning the crosslinkdensity of the coating, its thickness, or its composition. This can, forexample, be used to control the ripening of postharvest fruit orproduce. For example, coatings formed of plant extract compositions thatprimarily include bifunctional or polyfunctional cutin monomer unitscan, for example, have higher crosslink densities than those thatinclude monofunctional cutin monomer units. Thus, plant extractcomposition coatings formed from bifunctional or polyfunctional cutinmonomer units can in some cases result in slower rates of ripening ascompared to coatings formed from monofunctional monomer units.

In some embodiments, an acid or a base can be added to the coatingformulation to achieve a desired pH suitable for coating theagricultural product with the plant extract composition coating. In someembodiments, additives such as, for example, surfactants, emulsifiers,thickening agents, nonionic polymers, waxes, or salts can be included inthe coating formulation. In some embodiments, weak acids, ions, ornon-reactive molecules can be included in the coating formulation tocontrol or adjust the properties of the resulting films or coatings. Insome embodiments, pH stabilizers or modifiers can also be included inthe coating formulation. In some embodiments, the coating formulationcan include additional materials that are also transported to thesurface with the coating, or are deposited separately and aresubsequently encapsulated by the coating (e.g., the coating is formed atleast partially around the additional material), or are depositedseparately and are subsequently supported by the coating (e.g., theadditional material is anchored to the external surface of the coating).Examples of such additional materials can include cells, biologicalsignaling molecules, vitamins, minerals, pigments, aromas, enzymes,catalysts, antifungals, antimicrobials, and/or time-released drugs. Theadditional materials can be non-reactive with surface of theagricultural product and/or coating, or alternatively can be reactivewith the surface and/or coating.

In some embodiments, the coating can include an additive configured, forexample, to modify the viscosity, vapor pressure, surface tension, orsolubility of the coating. In some embodiments, the additive can beconfigured to increase the chemical stability of the coating. Forexample, the additive can be an antioxidant configured to inhibitoxidation of the coating. In some embodiments the additive can be addedto reduce or increase the melting temperature or the glass-transitiontemperature of the coating. In some embodiments, the additive can beconfigured to reduce the diffusivity of water vapor, oxygen, CO₂, orethylene through the coating or enable the coating to absorb more ultraviolet (UV) light, for example to protect the agricultural product(e.g., any of the products described herein). In some embodiments, theadditive can be configured to provide an intentional odor, for example afragrance (e.g., smell of flowers, fruits, plants, freshness, scents,etc.). In some embodiments, the additive can be configured to providecolor and can include, for example, a dye or a US Food and DrugAdministration (FDA) approved color additive. In some embodiments, theadditives can include sweeteners, color additives, flavors, spices,flavor enhancers, fat replacers, and components of formulations used toreplace fats, nutrients, emulsifiers, bulking agents, cleansing agents,stabilizers, emulsion stabilizers, thickeners, flavor or fragrance, aningredient of a flavor or fragrance, binders, texturizers, humectants,pH control agents, acidulants, leavening agents, anti-caking agents,antifungal agents, antimicrobial agents, antioxidants, and/or UVfilters. In some embodiments, the coating can include a photoinitiator,which can initiate crosslinking of the coating on exposure to anappropriate light source, for example, UV light.

In some embodiments, any of the plant extract composition coatingsdescribed herein can be flavorless or have high flavor thresholds, e.g.above 500 ppm, and can be odorless or have a high odor threshold. Insome embodiments, the materials included in any of the coatingsdescribed herein can be substantially transparent. For example, theplant extract composition, the solvent, and/or any other additivesincluded in the coating can be selected so that they have substantiallythe same or similar indices of refraction. By matching their indices ofrefraction, they may be optically matched to reduce light scattering andimprove light transmission. For example, by utilizing materials thathave similar indices of refraction and have a clear, transparentproperty, a coating having substantially transparent characteristics canbe formed.

Any of the coatings described herein can be disposed on the externalsurface of an agricultural product using any suitable means. Forexample, in some embodiments, the agricultural product can be dip-coatedin a bath of the coating formulation (e.g., an aqueous or mixedaqueous-organic or organic solution of the plant extract composition).The deposited coating can form a thin layer on the surface of anagricultural product, which can protect the agricultural product frombiotic stressors, water loss, and/or oxidation. In some embodiments, thedeposited coating can have a thickness of less than about 1500 nm, suchthat the coating is transparent to the naked eye. For example, thedeposited coating can have a thickness of about 10 nm, about 20 nm,about 30 nm, about 40 nm, about 50 nm, about 100 nm, about 150 nm, about200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about450 nm, about 500 nm, about 550 nm, about 600 nm, about 650 nm, about700 nm, about 750 nm, about 800 nm, about 850 nm, about 900 nm, about950 nm, 1,000 nm, about 1,100 nm, about 1,200 nm, about 1,300 nm, about1,400 nm, or about 1,500 nm, inclusive of all ranges therebetween. Insome embodiments, the deposited coating can be uniformly deposited overthe agricultural product and free of defects and/or pinholes. In someembodiments, the dip-coating process can include sequential coating ofthe agricultural product in baths of coating precursors that can undergoself-assembly or covalent bonding on the agricultural product to formthe coating. In some embodiments, the coating can be deposited onagricultural products by passing the agricultural products under astream of the coating formulation (e.g., a waterfall of the liquidcoating). For example, the agricultural products can be disposed on aconveyor that passes through the stream of the coating formulation. Insome embodiments, the coating can be misted, vapor- or dryvapor-deposited on the surface of the agricultural product. In someembodiments, the coating can be configured to be fixed on the surface ofthe agricultural product by UV crosslinking or by exposure to a reactivegas, for example, oxygen.

In some embodiments, the plant extract composition coating can bespray-coated on the agricultural products. Commercially availablesprayers can be used for spraying the coating or precursors of thecoating onto the agricultural product. In some embodiments, the coatingformulation can be electrically charged in the sprayer beforespray-coating on to the agricultural product, such that the depositedcoating electrostatically and/or covalently bonds to the exteriorsurface of the agricultural product.

The coatings formed from plant extract compositions described herein canbe configured to prevent water loss or other moisture loss from thecoated portion of the plant, delay ripening, and/or prevent oxygendiffusion into the coated portion of the plant, for example, to reduceoxidation of the coated portion of the plant. The coating can alsoprotect the coated portion of the plant against biotic stressors, suchas, for example, bacteria, fungi, viruses, and/or pests that can infestand decompose the coated portion of the plant. Since bacteria, fungi andpests all identify food sources via recognition of specific molecules onthe surface of the agricultural product, coating the agriculturalproducts with the coating containing the plant extract compositions candeposit molecularly contrasting molecules on the surface of the portionof the plant, which can render the agricultural products unrecognizable.Furthermore, the coating can also alter the physical and/or chemicalenvironment of the surface of the agricultural product making thesurface unfavorable for bacteria, fungi or pests to grow. The coatingcan also be formulated to protect the surface of the portion of theplant from abrasion, bruising, or otherwise mechanical damage, and/orprotect the portion of the plant from photodegradation. The portion ofthe plant can include, for example, a leaf, a stem, a shoot, a flower, afruit, a root, etc. In some embodiments, the coating can be used to coatfruits and, for example, delay ripening of the fruit.

Any of the coatings described herein can be disposed on the externalsurface of an agricultural product using any suitable means. Forexample, in some embodiments, the agricultural product can be dip coatedin a bath of the coating composition (e.g., an aqueous solution ofhydrogen-bonding organic molecules). The coating can form a thin layeron the surface of agricultural product, which can protect theagricultural product from biotic stressors, water loss, and/oroxidation. In some embodiments, the deposited coating can have athickness of less than about 2 microns, for example less than 1 micron,less than 900 nm, less than 800 nm, less than 700 nm, less than 600 nm,less than 500 nm, less than 400 nm, less than 300 nm, less than 200 nm,or less than 100 nm, such that the coating is transparent to the nakedeye. For example, the deposited coating can have a thickness of about 50nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm,150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 600 nm,700 nm, 800 nm, 900 nm, or about 1,000 nm inclusive of all rangestherebetween. The deposited coating can have a high degree ofcrystallinity to decrease permeability, such that the coating isconformally deposited over the agricultural product and is free ofdefects and/or pinholes. In some embodiments, the dip coating processcan include sequential coating of the agricultural product in baths ofprecursors that can undergo self-assembly or covalent bonding on theagricultural product to form the coating. In some embodiments, thecoatings can be deposited on agricultural products by passing theagricultural products under a stream of the coating (e.g., a waterfallof the liquid coating). For example, the agricultural products can bedisposed on a conveyor that passes through the stream of the coating. Insome embodiments, the coating can be vapor deposited on the surface ofthe agricultural product. In some embodiments, the coating can beformulated to be fixed on the surface of the agricultural product by UVcross-linking or by exposure to a reactive gas, for example, oxygen. Insome embodiments, the coating can be applied in the field before harvestas an alternative to pesticides.

In some embodiments, the fatty acid esters and/or oligomers thereof aredissolved in a suitable solvent (e.g., water, ethanol, or a combinationthereof) prior to coating the agricultural product. In some embodimentsthe process of disposing the composition on the agricultural productcomprises dip-coating the agricultural product in a solution comprisingthe plurality of cutin-derived monomers, oligomers, or combinationsthereof. In some embodiments the process of disposing the composition onthe agricultural product comprises spray-coating the produce with asolution comprising the plurality of fatty acid esters and/or oligomersthereof.

In some embodiments, any of the coatings can be spray coated on theagricultural products. Commercially available sprayers can be used forspraying the coating or precursors of the coating onto the agriculturalproduct. In some embodiments, the coatings can be electrically chargedin the sprayer before spray coating on the agricultural product, suchthat the coating covalently bonds to the exterior surface of theagricultural product.

In some embodiments, the coating can be deposited on the agriculturalproduct such that the coating is unbound to the surface of theagricultural product. In some embodiments, one or more components of thecoating, for example, the hydrogen-bonding organic molecule, can becovalently (or hydrogen) bonded to at least a portion of the surface ofthe agricultural product. This can result in improved coating propertiessuch as, for example, higher durability, tighter control of coatingpermeability and thickness. In some embodiments, multiple layers of thecoating can be deposited on the surface of agricultural product toachieve a durable coating.

Any of the coatings described herein can be used to protect anyagricultural product. In some embodiments, the coating can be coated onan edible agricultural product, for example, fruits, vegetables, edibleseeds and nuts, herbs, spices, produce, meat, eggs, dairy products,seafood, grains, or any other consumable item. In such embodiments, thecoating can include components that are non-toxic and safe forconsumption by humans and/or animals. For example, the coating caninclude components that are U.S. Food and Drug Administration (FDA)approved direct or indirect food additives, FDA approved food contactsubstances, satisfy FDA regulatory requirements to be used as a foodadditive or food contact substance, and/or is an FDA GenerallyRecognized as Safe (GRAS) material. Examples of such materials can befound within the FDA Code of Federal Regulations Title 21, located at“http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm”,the entire contents of which are hereby incorporated by referenceherein. In some embodiments, the components of the coating can include adietary supplement or ingredient of a dietary supplement. The componentsof the coating can also include an FDA approved food additive or coloradditive. In some embodiments, the coating can include components thatare naturally derived, as described herein. In some embodiments, thecoating can be flavorless or have a high flavor threshold of below 500ppm, are odorless or have a high odor threshold, and/or aresubstantially transparent. In some embodiments, the coating can beconfigured to be washed off an edible agricultural product, for example,with water.

In some embodiments, the coatings described herein can be formed on aninedible agricultural product. Such inedible agricultural products caninclude, for example, inedible flowers, seeds, shoots, stems, leaves,whole plants, and the like. In such embodiments, the coating can includecomponents that are non-toxic, but the threshold level for non-toxicitycan be higher than that prescribed for edible products. In suchembodiments, the coating can include an FDA approved food contactsubstance, an FDA approved food additive, or an FDA approved drugingredient, for example, any ingredient included in the FDA's databaseof approved drugs, which can be found at“http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm”, theentire contents of which are hereby incorporated herein by reference. Insome embodiments, the coating can include materials that satisfy FDArequirements to be used in drugs or are listed within the FDA's NationalDrug Discovery Code Directory,“http://www.accessdata.fda.gov/scripts/cder/ndc/default.cfm”, the entirecontents of which are hereby incorporated herein by reference. In someembodiments, the materials can include inactive drug ingredients of anapproved drug product as listed within the FDA's database,“http://www.accessdata.fda.gov/scripts/cder/ndc/default.cfm”, the entirecontents of which are hereby incorporated herein by reference.

Embodiments of the coatings described herein provide several advantages,including, for example: (1) the coatings can protect the agriculturalproducts from biotic stressors, i.e. bacteria, viruses, fungi, or pests;(2) the coatings can prevent evaporation of water and/or diffusion ofoxygen; (3) coating can help extend the shelf life of agriculturalproducts, for example, postharvest produce, without refrigeration; (4)the coatings can introduce mechanical stability to the surface of theagricultural products eliminating the need for expensive packagingdesigned to prevent the types of bruising which accelerate spoilage; (5)use of agricultural waste materials to obtain the coatings can helpeliminate the breeding environments of bacteria, fungi, and pests; (6)the coatings can be used in place of pesticides to protect plants,thereby minimizing the harmful impact of pesticides to human health andthe environment; (7) the coatings can be naturally derived and hence,safe for human consumption. Since the components of the coatingsdescribed herein can in some embodiments be obtained from agriculturalwaste, such coatings can be made at a relatively low cost. Therefore,the coatings can be particularly suited for small scale farmers, forexample, by reducing the cost required to protect crops from pesticidesand reducing postharvest losses of agricultural products due todecomposition by biotic and/or environmental stressors.

In some embodiments, the treating of the crosslinked polymer and/orforming of the plant extract composition is carried out by a firstparty, while the application of the plant extract composition to anagricultural product to form a protective coating over the agriculturalproduct is carried out by a second party different from the first party.For example, a manufacturer of the plant extract compositions (i.e., afirst party) can form the compositions by one or more of the methodsdescribed herein. The manufacturer can then sell or otherwise providethe resulting plant extract composition to a second party, for example afarmer, shipper, distributor, or retailer of produce, and the secondparty can apply the composition to one or more agricultural products toform a protective coating over the products. Alternatively, themanufacturer can sell or otherwise provide the resulting plant extractcomposition to an intermediary party, for example a wholesaler, who thensells or otherwise provides the plant extract composition to a secondparty such as a farmer, shipper, distributor, or retailer of produce,and the second party can apply the composition to one or moreagricultural products to form a protective coating over the products.

In some cases where multiple parties are involved, the first party mayoptionally provide instructions or recommendations about the extractcomposition, either written or oral, indicating one or more of thefollowing: (i) that the composition is intended to be applied to aproduct for the purpose of coating or protecting the product, to extendthe life of the product, to reduce spoilage of the product, or to modifyor improve the aesthetic appearance of the product; (ii) conditionsand/or methods that are suitable for applying the compositions to thesurfaces of products; and/or (iii) potential benefits (e.g., extendedshelf life, reduced rate of mass loss, reduced rate of molding and/orspoilage, etc.) that can result from the application of the compositionto a product. While the instructions or recommendations may be suppliedby the first party directly with the plant extract composition (e.g., onpackaging in which the composition is sold or distributed), theinstructions or recommendations may alternatively be suppliedseparately, for example on a website owned or controlled by the firstparty, or in advertising or marketing material provided by or on behalfof the first party.

In view of the above, it is recognized that in some cases, a party thatmanufactures a plant extract composition according to one or moremethods described herein (i.e., a first party) may not directly form acoating over a product from the extract composition, but can insteaddirect (e.g., can instruct or request) a second party to form a coatingover a product from the extract composition. That is, even if the firstparty does not coat a product by the methods and compositions describedherein, the first party may still cause the plant extract composition tobe applied to the product to form a protective coating over the productby providing instructions or recommendations as described above.Accordingly, as used herein, the act of applying a plant extractcomposition to a product (e.g., a plant or agricultural product) alsoincludes directing or instructing another party to apply the plantextract composition to the product, or causing the plant extractcomposition to be applied to the product.

The following examples describe plant extract compositions and methodsfor obtaining the same. These examples are only for illustrativepurposes and are not meant to limit the scope of the present disclosure.

Examples

In each of the examples below, all reagents and solvents were purchasedand used without further purification unless specified. All reactionswere carried out under an atmosphere of nitrogen with commercial gradesolvents unless otherwise stated. Reactions were monitored by thin layerchromatography (TLC) carried out on 0.25 mm E. Merck silica gel plates(60 Å, F-254) using UV light as the visualizing agent and an acidicmixture of anisaldehyde, ceric ammonium molybdate, or basic aqueouspotassium permanganate (KMnO₄), and heat as developing agents. NMRspectra were recorded on a Bruker Avance 500 MHz and/or Varian VNMRs 600MHz instruments and calibrated using residual un-deuterated solvent asan internal reference (eg. CHCl₃@ 7.26 ppm ¹H NMR, 77.16 ppm ¹³C NMR).The following abbreviations (or combinations thereof) were used toexplain the multiplicities: s=singlet, d=doublet, t=triplet, q=quartet,m=multiplet, br=broad. Mass spectra (MS) were recorded on a Waters XevoUPLC equipped with a Cis column and a ESI TQD MS. Absolute ethanol wasdried to low residual water according to the procedures in Purificationof Laboratory Chemicals (7^(th) ed.)

Example 1: Method for Preparing Tomato Pomace Prior to Depolymerization

Tomato pomace obtained from a commercial tomato processing facility wasmilled in a cutting mill, and sifted to give different particle sizedistributions (eg. >500 μm, 250-500 μm, 125-250 μm, etc.). The fractioncorresponding to 250-500 μm was sequentially extracted with CHCl₃overnight in a Soxhlet extractor and with methanol overnight in aSoxhlet extractor to remove the surface waxes and other solublecomponents, followed by drying under vacuum (<1 torr). The washed pomacewas then lyophilized overnight (<0.02 torr) to remove water, and thenstored in a desiccator before use.

Example 2: Method for Preparing a Composition from Tomato Skin/PeelTreated in a Base and an Alcohol

A general procedure for base catalyzed depolymerization is as follows.To depolymerize the dried and washed pomace, an ethanolic solutionincluding a stoichiometric excess (relative to tomato pomace) of sodiumethoxide was prepared in an oven dried three neck round bottom by adding2 eq. sodium metal (rel. to tomato pomace, assuming that the mass isentirely composed of cutin polymer) to 250 mL anhydrous ethanol under anitrogen atmosphere. The mixture was stirred under nitrogen until thesodium had completely dissolved, after which 10.0 g of the tomato pomace(250-500 m in size) was added against a counter-flow of nitrogen. Themixture was refluxed under nitrogen for 48 hours, followed by coolingthe reaction to room temperature and quenching it with 3 mL glacialacetic acid to a pH of about 7. The resulting solution was filteredusing Grade 1 Whatman filter paper to remove any leftover solids and thefiltrate was collected. Any excess solvent was removed from the filteredsolution by rotary evaporation. The crude isolate was dried under highvacuum (<0.1 torr), and was analyzed by UPLC and NMR. The crude isolatewas found to contain (9)10,16-dihydroxypalmitic acid, with no evidenceof ethyl ester formation.

Example 3: Method for Preparing a Composition from Tomato Skin/PeelTreated in an Acid and an Alcohol

To 250 mL of absolute ethanol was added sulfuric acid (7.36 g, 4.00 mL,75.0 mmol) and tomato pomace (10.0 g, 500 m-250 m in size) withstirring. The reaction was then heated to reflux for 48 hours. Oncecomplete, the reaction was cooled and the solution neutralized to pH 7with ˜70 mL sat. NaHCO₃(aq). The neutralized mixture was then filteredthrough a Buchner funnel and Grade 1 Whatman (70 mm) filter paper. Thefiltrate was dried by sequential rotary evaporation and high vacuum(<0.1 torr). When the crude material was dry, it was taken up in ethylacetate (140 mL) and three forward extractions were conducted with H₂O(2×160 mL) and brine (160 mL). The organic layer was separated, and thecombined aqueous phases were extracted with an additional 200 mL ethylacetate, and the organic phases combined, and dried with MgSO₄. Thesolvent was removed with rotary evaporation and high vacuum, yielding3.35 g (avg.) of crude isolate.

The crude isolate from the ethanolysis was dissolved in methanol, andthree times the mass of the crude isolate in Celite 545 was added. Themethanol was removed by rotary evaporator and dried Celite admixturetransferred to a cellulose extraction thimble. Glass wool was placed ontop of the material to ensure it stayed in the thimble. The material wasextracted in a Soxhlet extractor for 20 hours under nitrogen with 600 mLof heptane. After 20 hours, the Soxhlet apparatus and contents werecooled. The Soxhlet apparatus was then dismantled, and the round bottomwas placed in a fumehood overnight, which allowed a first crop of ethyl10,16-dihydroxyhexdecanoate (EtDHPA) to precipitate out of the heptane.The round bottom was then placed in a 2° C. fridge overnight, giving asecond crop of EtDHPA. The second crop was then filtered and transferredto a scintillation vial. Both crops were dried by sequential treatmentwith a rotary evaporator and high vacuum (<0.1 torr), resulting in ayellowish (first crop)/white (second crop) powder. Both crops wereanalyzed by NMR and UPLC/ESI MS, matching the expected spectra forEtDHPA; yield (combined crops): 0.76 g. ¹H NMR (600 MHz, Chloroform-d) δ4.11 (q, J=7.1 Hz, 2H), 3.63 (t, J=6.8 Hz, 2H), 3.57 (s, 1H), 2.27 (t,J=7.6 Hz, 2H), 1.66-1.51 (m, 6H), 1.49-1.25 (m, 21H), 1.24 (t, J=7.1 Hz,3H). See FIG. 12 (UPLC) and FIG. 13 (NMR).

Example 4: Method for Preparing a Composition from Tomato Skin/PeelTreated in an Acid and an Alcohol at High Temperatures

To a thick-walled sealed tube containing 250 mL of absolute ethanol wasadded sulfuric acid (7.36 g, 4.00 mL, 75.0 mmol), followed by tomatopomace (10.0 g, 500 m-250 m in size). The reaction was then heated totemperatures greater than the atmospheric boiling point of ethanol, suchas 100° C. or 120° C. for 24 or 48 hours. Once complete, the reactionwas cooled and the solution neutralized to pH 7 with ˜70 mL sat.NaHCO₃(aq.). The neutralized mixture was then filtered through a Buchnerfunnel and Grade 1 Whatman (70 mm) filter paper. The filtrate was driedby sequential rotary evaporation and high vacuum (<0.1 torr). When thecrude material was dry, it was taken up in ethyl acetate (140 mL), andthree forward extractions were conducted with H₂O (2×160 mL) and brine(160 mL). The organic layer was separated, and the combined aqueousphases were extracted with an additional 200 mL ethyl acetate, and theorganic phases combined, and dried with MgSO₄. The solvent was removedwith rotary evaporation and high vacuum, yielding the crude isolate. Theamounts of crude recovered at each of the different temperature and timeconditions are plotted in FIG. 5.

The crude isolate obtained from the ethanolysis was dissolved inmethanol, and three times the mass of the crude isolate in Celite 545was added. The methanol was removed by rotary evaporator and the driedCelite admixture transferred to a cellulose extraction thimble. Glasswool was placed on top of the material to ensure it stayed in thethimble. The material was extracted for 20 hours under nitrogen in aSoxhlet extractor with 500 mL of heptane and then cooled. The Soxhletapparatus was then dismantled and the round bottom was placed in thefumehood overnight, which allowed a first crop of EtDHPA to precipitateout of the heptane. The round bottom was then placed in a 4° C. fridgeovernight, providing a second crop of EtDHPA. This precipitate was thenfiltered and transferred to a scintillation vial. Both crops were driedby sequential treatment with a rotary evaporator and high vacuum (<0.1torr) to give a white/yellowish powder. Both crops were analyzed by NMRand UPLC/ESI MS, matching the expected spectra for EtDHPA. The amountsrecovered of the EtDHPA isolate are shown in FIGS. 5 and 6.

While various embodiments of the system, methods and devices have beendescribed above, it should be understood that they have been presentedby way of example only, and not limitation. Where methods and stepsdescribed above indicate certain events occurring in certain order,those of ordinary skill in the art having the benefit of this disclosurewould recognize that the ordering of certain steps may be modified andsuch modification are in accordance with the variations of theinvention. Additionally, certain of the steps may be performedconcurrently in a parallel process when possible, as well as performedsequentially as described above. The embodiments have been particularlyshown and described, but it will be understood that various changes inform and details may be made. Accordingly, other implementations arewithin the scope of the following claims.

1. A method of preparing a composition comprising fatty acid esters, themethod comprising: providing a crosslinked polyester comprisingpolymerized mono- or polyhydroxy fatty acids; treating the crosslinkedpolyester with an acid and an alcohol; removing the acid and the alcoholto form a mixture comprising the fatty acid esters; and purifying themixture to isolate the fatty acid esters.
 2. The method of claim 1,wherein the crosslinked polyester is naturally occurring.
 3. The methodof claim 1, wherein the crosslinked polyester is derived from plantmatter.
 4. The method of claim 1, wherein the crosslinked polyester iscutin.
 5. The method of claim 4, wherein the cutin is derived from plantskins.
 6. The method of claim 1, wherein the crosslinked polyestercontains endogenous water.
 7. The method of claim 6, wherein the methodis characterized as only requiring a single step to obtain the mixturecomprising the fatty acid esters from the crosslinked polyester.
 8. Themethod of claim 1, wherein the alcohol comprises ethanol, methanol,propanol, glycerol, or isopropanol.
 9. The method of claim 1, whereinremoving the acid comprises neutralizing the acid.
 10. The method ofclaim 1, wherein removing the alcohol comprises evaporating the alcohol.11. The method of claim 1, wherein the acid is sulfuric acid, triflicacid, hydrochloric acid, hydrobromic acid, hydroiodic acid,para-toluenesulfonic acid, or a combination thereof.
 12. The method ofclaim 1, wherein the acid is combined with the alcohol insuperstoichiometric amounts.
 13. The method of claim 1, wherein thefatty acids of the crosslinked polymer comprise 16-hydroxyhexadecanoicacid, 9,16-dihydroxyhexadecanoic acid, 10,16-dihydroxyhexadecanoic acid,18-hydroxyoctadecanoic acid, 18-hydroxy-(9Z)-octadec-9-enoic acid,9,10-epoxy-18-hydroxyoctadecanoic acid, 9,10,18-trihydroxyoctadecanoicacid, or a combination thereof.
 14. The method of claim 1, wherein theisolated fatty acid esters comprise ethyl 16-hydroxyhexadecanoate, ethyl9,16-dihydroxyhexadecanoate, ethyl 10,16-dihydroxyhexadecanoate, ethyl18-hydroxyoctadecanoate, ethyl 18-hydroxy-(9Z)-octadec-9-enoate, ethyl9,10-epoxy-18-hydroxyoctadecanoate, ethyl9,10,18-trihydroxyoctadecanoate, or a combination thereof.
 15. Themethod of claim 1, where the composition is in the form of a solidpowder.
 16. The method of claim 15, wherein the powder has nosubstantial coloration.
 17. A method of preparing a compositioncomprising cutin-derived monomeric or oligomeric esters, the methodcomprising: adding cutin to a solvent comprising an acid and an alcohol;removing the solvent to form a mixture comprising the cutin-derivedmonomeric or oligomeric esters; and purifying the mixture to isolate thecutin-derived monomeric or oligomeric esters; wherein the cutin-derivedmonomeric or oligomeric esters comprise one or more compounds of FormulaI:

wherein: R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ are eachindependently —H, —OR¹³, —NR¹³R¹⁴, —SR¹³, halogen, —C₁-C₆ alkyl, —C₁-C₆alkenyl, —C₁-C₆ alkynyl, —C₃-C₇ cycloalkyl, aryl, or 5- to 10-memberedring heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl,or heteroaryl is optionally substituted with —OR¹³, —NR¹³R¹⁴, —SR¹³, orhalogen; R¹³ and R¹⁴ are each independently —H, —C₁-C₆ alkyl, —C₁-C₆alkenyl, or —C₁-C₆ alkynyl; R¹¹ is -glyceryl, —C₁-C₆ alkyl, —C₁-C₆alkenyl, —C₁-C₆ alkynyl, —C₃-C₇ cycloalkyl, aryl, or 5- to 10-memberedring heteroaryl, wherein each alkyl, alkenyl, alkynyl, cycloalkyl, aryl,or heteroaryl is optionally substituted with —OR¹³, —NR¹³R¹⁴, —SR¹³, orhalogen; R¹² is —OH, —H, —C₁-C₆ alkyl, —C₁-C₆ alkenyl, —C₁-C₆ alkynyl,—C₃-C₇ cycloalkyl, aryl, or 5- to 10-membered ring heteroaryl, whereineach alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or heteroaryl isoptionally substituted with —OR¹³, —NR¹³R¹⁴, —SR¹³, halogen, —COOH, or—COOR¹; and m, n, and o are each independently an integer in the rangeof 0 to 30, and 0≤m+n+o≤30.
 18. The method of claim 17, wherein thecutin contains endogenous water.
 19. The method of claim 18, wherein themethod is characterized as only requiring a single step to obtain themixture comprising the cutin-derived monomeric or oligomeric esters fromthe cutin.
 20. The method of claim 17, wherein the alcohol comprisesethanol, methanol, propanol, glycerol, or isopropanol.
 21. The method ofclaim 17, wherein the acid is combined with the alcohol insuperstoichiometric amounts.
 22. The method of claim 17, where thecomposition is in the form of a solid powder.
 23. The method of claim22, wherein the powder has no substantial coloration.
 24. A method offorming a protective coating on a substrate, comprising: obtaining fattyacid esters, the obtaining of the fatty acid esters comprising: treatinga crosslinked polyester comprising polymerized mono- or polyhydroxyfatty acids with an acid and an alcohol; removing the acid and thealcohol to form a mixture; and purifying the mixture to isolate theresulting fatty acid esters; and causing the fatty acid esters to beapplied to a surface of the substrate to form the protective coating.25. The method of claim 24, where the composition is in the form of asolid powder.
 26. The method of claim 25, wherein the powder has nosubstantial coloration.
 27. The method of claim 24, wherein thecrosslinked polyester comprises cutin.
 28. The method of claim 24,wherein the substrate is an edible substrate.
 29. The method of claim24, wherein the substrate comprises produce.
 30. The method of claim 24,wherein the substrate comprises plant matter.